The boy was naked and curled in a fetal position when El Dorado County Deputy Rich Strasser discovered the wreckage on Saturday morning. Strasser said he assumed the child was dead, but checked for vital signs and found he was breathing.

The child was taken to the UC Davis Medical Center in Sacramento. By late Sunday, his condition was upgraded from critical to fair, and his release is expected within days.

"Nicky's starting to remember things," said Karen Nichols-Daniels, a great-aunt. "He said there was a tree lying on his mommy and he said he couldn't open the door."

The car plunged off the highway east of Sacramento and wound up at the bottom of a 40-foot embankment. The roof was torn off.

Strasser said that Christene Skubish probably died instantly.

The boy was covered with scratches and had blisters from exposure to poison oak, Nichols-Daniels said.

Strasser had spotted the boy's tennis shoe on the side of the highway Saturday, and then found the car. He believes the boy at some point climbed from the car to the highway, and then returned to the car. That is the only explanation for the shoe being on the road, Strasser said.

Certain mysteries remain about the case. Police were initially alerted by a motorist's report of a naked woman on U.S. 50. But no such woman was found. However, the boy was nude. His clothing was in the car, Strasser said.